


Water Balloon Fight

by Dragonsrule18



Series: Tumblr Prompts [6]
Category: Undertale (Video Game)
Genre: Alphyne, Alphys/Undyne-centric, At Water Balloon Fights At Least, Entire Undertale Cast - Freeform, Established Alphys/Undyne, F/F, F/M, Family Fluff, Female Frisk, Fluff, Frisk is a Sweetheart, Frisk's Birthday, Gen, Mild Innuendo, Mild Language, No More Resets (Undertale), Papyrus And Undyne Are Best BroTP, Papyrus Being Papyrus, Post-Undertale Pacifist Route - "I want to stay with you.", Romantic Fluff, Sans Being Sans, Sans Makes Puns, Sans is a Cheater, Summer, Teenage Frisk, Tooth-Rotting Fluff, Undertale Monsters on the Surface, Water Balloon Fights, summer fun
Language: English
Status: Completed
Published: 2018-06-07
Updated: 2018-06-07
Packaged: 2019-05-19 10:59:59
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,217
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14872502
Author URL: https://archiveofourown.org/users/Dragonsrule18/pseuds/Dragonsrule18
Summary: My response to the Tumblr prompt, "We need more water balloons!"  Undyne and Papyrus start a giant water balloon fight at Frisk's seventeenth birthday party.  Alphys isn't sure at about it at first, but finds out she's far better at water balloons than she thought.  Undyne is impressed.   Pointless, plotless Alphyne summer fun for Omoni and AngleJoyce.





	Water Balloon Fight

**Author's Note:**

  * For [Omoni](https://archiveofourown.org/users/Omoni/gifts), [AngleJoyce](https://archiveofourown.org/users/AngleJoyce/gifts).



It was a beautiful, peaceful, day and Alphys was happily relaxing in a lawn chair as she watched the party going on around her, wating for Undyne to come back from whatever she was doing. It was Frisk's seventeenth birthday and her friends and family had thrown her a huge barbecue, complete with enough food to feed all the monsters in the Underground twice, games, and of course, presents.

Right now, Frisk was playing horseshoes with Papyrus, competing to see who could get the best shot and laughing together, Toriel and Muffet were arguing over what was the right amount of snails to put in in a pie, Sans was fast asleep under the picnic table(no one knew why), Asgore was grilling, and Mettaton was trying to coax Shyren onto the makeshift stage to help him sing a song for the birthday girl.

All was peaceful.

And then the first water balloon went flying.

Alphys jumped about a mile as it sailed over her head and crashed into an unsuspecting Papyrus's shoulder, making him yelp as the icy cold water soaked his Cool Dude T-shirt. He whirled around to see who had thrown that.

Undyne was laughing, a giant bucket of water balloons beside her. "Gotcha!"

Papyrus mock glared at her. "THIS MEANS WAR!" he proclaimed. "HUMAN! SANS! YOU'RE ON MY TEAM!" He picked up a giggling Frisk with one arm while pulling his now awake and amused brother out from under the table with the other.

Undyne's eye sparked with her competitive spirit. "Alphy, you're with me!" she said, scooping up her girlfriend from her lawn chair, making her yelp.

"U-Undyne, I'm not that fast...or strong...I might not be the best choice for a teammate in a water balloon fight..." Alphys protested.

"Alphys, you're awesome! You'll be great at this! C'mon, it'll be fun!" Undyne encouraged and gave her the puppy dog eyes, well, eye.

Alphys gave in. "All right..."

"Yes! Now who else wants to join?"

Asgore joined Undyne and Alphys while Toriel joined Papyrus' and Sans's side. Mettaton had to be goaded into joining by Undyne and Muffet was coaxed into joining Papyrus's side. The other monsters divided themselves onto the sides of the people they liked best, though fire monsters like Grillby, Vulkin, and Pyrope stayed as far away from the water balloon fight as possible.

A second bucket was quickly filled with water balloons and the two sides prepared for battle.

"OKAY, GET READY, GET SET..." Papyrus started.

"GO!" Undyne yelled and of course threw the first water balloon. This time Papyrus was ready and ducked, hurling a water balloon at Undyne that hit her square in the chest.

"Oh, it's on! NGAHHHHH!" Undyne yelled, charging ahead. The other monsters on her team took her lead, though Alphys was a bit behind, and the monsters on Papyrus's team took this as their cue to charge too, both sides hurtling water balloons at each other.

Ten minutes in, almost everyone was soaked. Asgore looked like a drowned cat due to Toriel who threw water balloons the way she had once thrown fireballs(though this was much more gentle) and a laughing Asgore had gotten her good a few times too. Mettaton had stepped out of the fight after getting soaked by a water balloon, muttering something about not wanting to rust his beautiful body and Muffet had run off to rescue her spiders and pastries after a wild shot had landed way too close to the dessert table. Alphys was soaked to the bone too, though loyally remained with Undyne, doing more watching than actual water balloon throwing and helping by getting water balloons to her girlfriend, who, due to her love of being on the front lines, was more soaked than almost anyone except for Papyrus and Frisk, who fought on the front lines as a team.

Though there was one person who hadn't gotten wet.

Sans, the smug asshole, kept teleporting out of the way whenever a water balloon was aimed his way. Of course, Undyne took this as a challenge, and he became her sole target now that she realized he was the only one who hadn't gotten a water balloon to the kisser.

"We need more water balloons!" Undyne called.

Alphys nodded and rushed to get them, narrowly dodging a water balloon from Sans. She returned with four. "This is all we have left."

"Dammit. We'll have to make each shot count then!" Undyne muttered and took two from Alphys, leaving her girlfriend with two. She hurled one at Sans, only for him to teleport to the left and the water balloon hit Frisk instead.

"VENGEANCE!" Papyrus yelled playfully and threw his last water balloon at Undyne, who was hit, but the determined fish was more focused on Sans. She threw another one at him and he teleported to the left again, ending up very close to the fence.

"Alphys! It's up to you now!" Undyne told her girlfriend.

Alphys knew she didn't have as good of an arm as her girlfriend, but she had an idea as she had spent most of her time observing the water balloon fight. She threw a water balloon at Sans with all her strength, knowing he'd teleport, then, remembering his pattern of teleportation, rapidly threw a water balloon to the right at the usual distance Sans would reappear.

And it hit him right in the chest as he reappeared. He had a stunned look on his face, and both teams looked to Alphys in shock as no one else had been able to get Sans, and no one had expected timid Alphys, who had done more assisting than throwing water balloons, to be the one to do so.

No one except Undyne, that is.

Undyne broke the silence by cheering and laughing loudly, picking up Alphys and twirling her around, planting a passionate kiss on Alphys' lips, making the dinosaur turn beet red. "That was awesome! I KNEW you'd be great at this, Alph! Man, I wish someone had brought a video camera! That was the shot of the day!"

"I got it, darling!" Mettaton yelled from the sidelines, holding a video camera.

"Awesome! I take back everything I said about you before, Mettaton! You're great!" Undyne called out to him, a blissfully smiling love-struck Alphys still in her arms.

"Why thank you, da...Wait, what did she say about me before?" Mettaton asked, then just shrugged it off.

"Nice shot, Doc. You soaked me, right down to the bone." Sans told her, grinning.

"SANS!" Papyrus yelled, though he was holding back a laugh.

"Aww, c'mon bro, you're smiling." Sans told him.

"I AM AND I HATE IT!" Papyrus told him, though anyone who actually knew Papyrus would know that he didn't. "ANYWAY, WE ALL FOUGHT WITH HONOR TODAY, AND I BELIEVE IT'S TIME WE DRY OFF AND CUT FRISK'S BIRTHDAY CAKE."

"Sounds good to me." Undyne shrugged. "C'mon, Alph. I'll help you dry off." She then whispered into Alphys' ear so no one else could hear, "And then tonight we can celebrate your big win." Alphys turned bright red and nodded eagerly before going with Undyne to grab some towels.

Frisk leaned against Papyrus, who wrapped his arm around her. "Best birthday ever." she said with a smile.

**Author's Note:**

> Hope you guys enjoyed this response to the Tumblr prompt! If anyone has any requests for a Tumblr prompt or pairing you'd like to see me do, let me know in the comments below. I do take requests, though I have the right to refuse any that make me uncomfortable.


End file.
